Although I can only provide speculation, this situation seems intriguing, so I will provide my opinion.
In my observation, the MCT gearbox seems to be a conventional automatic gearbox without a torque converter, specifically located between the engine's output and the gearbox's input. The MCT bit refers to a novel technique (in this particular application) that use a clutch instead of a TC, similar to a wet clutch seen in motorcycles. The proof you have provided consists of two observations: 1) the presence of jerky movements during slow driving, and 2) the detection of metal particles resembling swarf on the magnetic pickup. The MCT clutch is composed of alternating metal plates and clutch plates, which slide together during operation. The use of 'wet' oil ensures that the clutch remains cool and prevents the accumulation of wear debris, which is directed away from the clutch and towards the filter to prevent any blockages. However, the origin of the metal fragments adhered to the magnet remains unknown - but from which source? If the gearbox oil is shared with the clutch oil, the source of the oil might be either: a) the MCT clutch, b) the different wet multi-plate clutches used for gear change in the gearbox, or c) another component such as a deteriorating bearing or gear. Based on the absence of any mention of abnormal sounds and the occurrence of slow speed jerkiness, it is possible that a malfunctioning MCT (Multi-Clutch Transmission) might be the cause. This could be attributed to excessive wear leading to metal-on-metal contact. The wet multi-plate clutch has shown its effectiveness in motorcycles and automatic transmissions, but it has not been extensively tested in very heavy and high-powered vehicles. Repeated instances of rapid acceleration with clutch slippage, such as during launch control events, can significantly reduce the lifespan of the clutch. In my own perspective, clutches (whether wet or dry) should be seen as a binary mechanism, where power should be gradually and swiftly applied, and only then fully engaged. Any alternative approach will inevitably result in the clutch being a regularly damaged component, similar to what happens with racing cars. On the contrary, a TC is specifically engineered to smoothly engage (and contemporary models engage firmly for optimal performance).